The present invention relates to a system having a control unit for triggering a restraint system, assigned to a seat of a vehicle, upon the recording of an event to be interpreted as an impact on an obstacle. The system includes a status acquisition device that is connected to the control unit via a transmission channel. In order to activate the triggering only when the condition is present, the status acquisition device, during operation, regularly transmits to the control unit a corresponding data record indicating the presence or non-presence. Furthermore, the present invention relates to a method for the testing/diagnosis of a system of this kind.
A control unit typically triggers the ignition of at least one propellant charge of an air bag when criteria have been recorded which are to be interpreted as an impact of a vehicle on an obstacle. In order to avoid unnecessary releases, using suitable recording devices, it is additionally determined whether a person to be protected is actually sitting in the respective seat, that is, whether the seat is occupied. The activation of such restraint systems, such as a front air bag, a side air bag, belt tensioners and the like, has also been made dependent upon other recordable conditions, for example, whether a sitting person is disposed in an ideal sitting position or not, and the like. Usually, information on the condition to be recorded is transmitted regularly in the form of a data record having digital signals, such as every 240 ms, via the transmission channel to the control unit, the transmission channel in practice being formed by a conductor. In order to ensure orderly functioning, it should be possible to make a test and a diagnosis. In such a diagnosis, it may be necessary to be able to allocate the diagnosis result uniquely to the tested device. In this connection, it is extremely desirable if the device submitted to a diagnosis can indeed be identified, even if it is built into the vehicle, perhaps also for carrying out statistical evaluations. For this, it may be necessary to be able to determine so-called type characteristics of the device to be tested, such as its serial number, manufacturing date, vendor and more of the like.
Up to now it has been necessary to register the appropriate type characteristics by hand, expediently before mounting the device on the vehicle, which is clearly very cumbersome and costly. The correction of the registered type characteristics, especially in the case of numerous devices, is no longer reliable once a vehicle has been delivered, and one or another status acquisition device has been exchanged. This is not even guaranteed if the vehicle is maintained in authorized repair shops.